Estimation of Interdependence Among Quarters of the Bovine Udder with Subclinical Mastitis and Implications for Analysis

• Published in: Journal of dairy science 1997-08, Vol.80 (8), p.1592-1599
• Main Authors: Barkema, H.W., Schukken, Y.H., Lam, T.J.G.M., Galligan, D.T., Beiboer, M.L., Brand, A.
• Format: Article
• Language: English
• Subjects: AETIOLOGY; AGENT PATHOGENE; Animal bacterial diseases; Animals; ASYMPTOMATIC INFECTIONS; Bacterial diseases; Biological and medical sciences; BOVINE MASTITIS; Cattle; Cell Count; CONTEO DE CELULAS SOMATICAS; CORRELATION; Corynebacterium - isolation & purification; Corynebacterium Infections - veterinary; DAIRY COWS; DISEASE PREVALENCE; ETIOLOGIA; ETIOLOGIE; Female; GLANDE MAMMAIRE; GLANDULAS MAMARIAS; INDIVIDUAL QUARTERS; INFECCIONES LATENTES; INFECTION LATENTE; Infectious diseases; interdependence; LATENT INFECTIONS; MAMMARY GLANDS; Mammary Glands, Animal - microbiology; Mammary Glands, Animal - pathology; MAMMITE BOVINE; mastitis; MASTITIS BOVINA; Mastitis, Bovine - microbiology; Mastitis, Bovine - pathology; Medical sciences; Milk - cytology; MINOR PATHOGENS; NUMERATION CELLULAIRE SOMATIQUE; ORGANISMOS PATOGENOS; PATHOGENS; quarter; SOMATIC CELL COUNT; Staphylococcal Infections - veterinary; STAPHYLOCOCCUS AUREUS; Staphylococcus aureus - isolation & purification; Streptococcal Infections - veterinary; STREPTOCOCCUS; Streptococcus - isolation & purification; Streptococcus agalactiae - isolation & purification; VACAS LECHERAS; VACHE LAITIERE; VARIANCE COMPONENTS
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(97)76089-2

Interdependency among udder quarters with subclinical mastitis was evaluated on 150 farms using a total of 35,828 udder quarters. The occurrence of high somatic cell count (SCC) (>250,000 cells/ml) in 0, 3, and 4 quarters occurred at a higher rate than would be expected based on independence of the quarters. For all bacterial species, intramammary infection in 0, 2, 3, or 4 quarters of the same cow occurred at a higher rate than would be expected based on independence of the quarters. Intramammary infection and high SCC were found less often in front quarters than in rear quarters. High SCC and intramammary infection occurred more often in right front quarters than in left front quarters. High SCC in diagonal quarters occurred at a lower rate than expected. Corynebacterium bovis, Streptococcus agalactiae, and Staphylococcus aureus had the highest intraclass correlation within herd. Streptococcus uberis had a very low intraclass correlation within herd. The intraclass correlation within cow for the natural logarithm of SCC was 0.47. Corynebacterium bovis and Strep. agalactiae had the highest intraclass correlation within cow, and Streptococcus dysgalactiae had the lowest. Analytical methods were proposed to manage the problem of interdependence and its effect on the design or evaluation of field studies on subclinical mastitis.